EAS system providing synchronized transmission

Abstract

A system and method for providing synchronized transmission in an electronic article surveillance (EAS) system is provided. The method includes determining a transmission timing difference between a plurality of units of the EAS system using a communication link of the EAS system and synchronizing transmissions for each of the plurality of units based on the transmission timing difference.

1. A method for synchronizing transmissions of a plurality of units in an electronic article surveillance (EAS) system, said method comprising:
 receiving timing information from each of the plurality of units in order to synchronize transmissions for each of the plurality of units, the plurality of units including a master unit and at least one non-master unit, the timing information of each of the plurality of units being based on a time period from receiving a broadcast message to a next interrogation/deactivation transmission of the corresponding unit to corresponding EAS tags; 
 determining transmission timing differences for each of the non-master units from which timing information was received, the transmission timing difference for each unit being based on the received timing information from the corresponding unit; and 
 transmitting a delay amount for each of the non-master units based on the determined timing difference for the corresponding unit, thereby synchronizing the transmissions for each of the units based on the transmission timing difference; 
 wherein the transmission timing difference for each non-master unit is based on the difference in timing information between the master synchronizing unit and the corresponding non-master unit. 
 
     
     
       2. A method in accordance with  claim 1  further comprising transmitting a broadcast message to the plurality of units based on a synchronizing event of the master synchronizing unit, each of the plurality of units initiating a synchronizing detection process to determine the corresponding timing information. 
     
     
       3. A method in accordance with  claim 2  wherein the synchronizing event is one of a zero crossing and a transmission start time. 
     
     
       4. A method in accordance with  claim 2  wherein the time period for each unit is based on a count value for each of the units, the start of the count corresponding to the receiving of the broadcast message and the end of the count corresponding to the next transmission of the corresponding unit. 
     
     
       5. A method in accordance with  claim 1  wherein the determining is performed iteratively. 
     
     
       6. A method in accordance with  claim 1  further comprising storing the transmission timing difference corresponding to each of the plurality of non-master units in a memory of each of the units. 
     
     
       7. A method in accordance with  claim 1  wherein the plurality of units comprise at least one of an EAS detector unit and an EAS deactivator unit. 
     
     
       8. A method in accordance with  claim 1  further comprising receiving a user input to select units for synchronizing. 
     
     
       9. A method in accordance with  claim 1  further comprising providing a user interface for receiving user inputs to control the synchronizing. 
     
     
       10. A method in accordance with  claim 1  wherein the EAS system comprises a serial network for communicating with each of the plurality of units. 
     
     
       11. A method for calibrating an electronic article surveillance (EAS) system to synchronize interrogation/deactivation transmissions of a plurality of units to corresponding EAS tags, said method comprising:
 selecting one of the plurality of units of the EAS system as a master synchronizing unit; 
 transmitting a broadcast signal to the plurality of units upon a synchronizing event of the master synchronizing unit; 
 determining for each of the plurality of units a time period from receiving the broadcast signal to a next interrogation/deactivation transmission of the corresponding unit; 
 determining a difference between the time period for the master synchronizing unit and each of the non-master units, the difference based on the corresponding determined time period for each of the plurality of units; 
 determining a delay for each of the non-master units based on the determined difference for the corresponding unit to synchronize transmissions for each of the non-master units; and 
 transmitting the corresponding delay to each of the non-master units. 
 
     
     
       12. A method in accordance with  claim 11  further comprising starting a counter within each of the units upon receiving the broadcast signal, the counter determining the time period. 
     
     
       13. A method in accordance with  claim 11  further comprising communicating with each of the units via a serial network. 
     
     
       14. A method in accordance with  claim 11  wherein the units comprise EAS detector units and EAS deactivator units. 
     
     
       15. An electronic article surveillance (EAS) system comprising:
 at least one of a plurality of detector units and at least one of a plurality of deactivator units connected via a communication link; and 
 a system controller configured to:
 (i) receive timing information from at least one of the plurality of detector units and deactivator units in order to synchronize transmissions for each of the plurality of units, the timing information of each unit based on a time period from receiving a broadcast message to a next interrogation/deactivation transmission of the corresponding unit; 
 (ii) determine transmission timing differences between a selected one of the plurality of units and non-selected units using the communication link, the transmission timing difference for each non-selected unit based on corresponding timing information; and 
 (iii) transmit a delay amount for each non-selected unit based on the determined corresponding timing difference for each non-selected unit thereby synchronizing transmissions for each of the plurality of units. 
 
 
     
     
       16. An EAS system in accordance with  claim 15  wherein each of the plurality of units is configured to measure the time period from receiving the broadcast message based on a synchronizing event of the selected unit to the next transmission of the corresponding unit, the time period determined using a counter within each of the units. 
     
     
       17. An EAS system in accordance with  claim 15  further comprising a user interface for controlling the synchronization, and wherein the user interface comprises a control portion and an analysis portion.